ABC News(NEW YORK) — Two storms are combining on Wednesday morning over the Mississippi Valley that are set to move east with heavy snow, ice and flooding rain through much of the day.

Over 1,000 flights had already been grounded before 6 a.m., and that was only expected to get much worse as the storm moved into Washington, the Mid-Atlantic and eventually the Northeast.

There are 35 states under snow, ice and flood alerts from Colorado to Maine on Wednesday.

The storms stretch from Minneapolis to Chicago and into Washington, D.C., where snow just began to fall prior to the morning commute.

Farther south, heavy rain and strong storms are moving through the Ohio, Tennessee and Mississippi River valleys.

Snow will be heavy at times throughout the day in the Twin Cities, where schools were closed for the day well ahead of time. A wintry mix is expected throughout the day in Chicago and Detroit, while snow will be heavy at times in Washington on Wednesday morning before changing to rain early in the afternoon.

In Philadelphia, snow will begin in the late morning and continue through the afternoon before it changes to rain during the evening rush hour.

New York City will see snow beginning before 2 p.m. and through the evening rush hour, but it will change to sleet and rain after 7 p.m. The snow will reach Boston well after the evening rush — around 10 p.m. Wednesday — and continue into the early overnight hours before changing to rain.

All of the major cities along the Interstate 95 corridor will eventually see rain before the precipitation ends at night.

The heaviest snow and ice will be in central Pennsylvania, and into West Virginia, western Maryland and Virginia, where up to 10 inches of snow is possible.

Washington will see about 5 inches, Philadelphia 3 to 4 inches, New York City 2 to 4 inches and Boston 2 to 3 inches.

Minneapolis could receive up to 10 inches of snow, while Chicago and Detroit will only see about an inch. There will be more to the north, into Wisconsin and central and northern Michigan.

Additional rain in the South — locally 1 to 3 inches is possible — could cause some flooding.